Thursday, April 10, 2008

My previous look at ethanol use for a big SUV tank approached the impossibly unrealistic - 560 pounds of corn to reduce the amount of gasoline filling the tank of an SUV by 1.6 gallons. Not very many people drive really huge SUVs, and NOBODY uses E85, especially SUV owners.

Here I take a look at fueling vehicles that are more common and fueled by something much more commonly used than E85.

THE SIMPLE ANSWER

Consider a full-size sedan, minivan or mid-size SUV using E10 fuel. In this case, 15 gallon can be a typical tank fill. Of the 15 gallons of E10 motor fuel, 10 percent, or 1.5 gallons, is ethanol.

Using the updated corn to ethanol conversion from the 2007 Ethanol Fact Book, it takes six-tenths of a bushel to produce that 1.5 gallon of ethanol (1.5 gallon divided by 2.5 gal. per bushel of corn). The 6/10 bushel is 33.6 pounds of corn.

So the simple answer is over 30 pounds of corn are taken off the plate of the proverbial Starving Child in Africa, every time you fill your Camry or Explorer.

STOP HERE - UNLESS YOU ARE A MATH GEEK

Looking deeper into ethanol use, the picture gets worse, in fact, much worse. Due to the energy density of ethanol (.66 the energy of gasoline by volume), 50.9 pounds (33.6 divided by .66) of corn are needed to replace the 1.5 gallons of gasoline displaced by ethanol.

Looking at production efficiencies, the 2007 Ethanol Fact Book now claims that the energy yield from ethanol production is 34% (a huge jump from the 2005 Fact Book, where they admitted only a 6% energy gain). Dividing 1.5 gallon by 1.34, we find that using 15 gallons of E10, only reduces gasoline imports by 1.1 gallons in that tank.

Therefore, the net benefit of using E10 motor fuel is a reduction of 1.1 gallons of gasoline for 50.9 pounds of corn used to make the ethanol. Multiply this by the millions of vehicle fill-ups each day in the U.S., and it is easy to see why food prices are skyrocketing, while oil imports are just barely creeping downward.

'That's how David Pimental, a researcher at Cornell University, characterizes corn-based ethanol production. 'Ethanol does not provide energy security for the future,' he says. 'It is not a renewable energy source, is costly in terms of production and subsidies, and its production causes serious environmental degradation.'

"According to Pimental's research, ethanol production actually CONSUMES energy. 'The total energy input to produce one gallon of ethanol is 129,600 BTU,' Pimental asserted in a 1998 research paper.

"'However, one gallon of ethanol has an energy value of only 76,000 BTU. Thus, a net energy loss of 53,600 BTU occurs for each gallon of ethanol produced. Put another way, about 71% more energy is required to produce a gallon of ethanol than the energy that is contained in a gallon of ethanol.'